Merge branch '4.3' into 4.4

* 4.3:
  [Cache] clean tags folder on invalidation
  [Cache] remove implicit dependency on symfony/filesystem
  Allow to set cookie_samesite to 'none'
  [VarDumper] fix array key error for class SymfonyCaster
  Adds missing translations for no nb
  [HttpKernel] fix $dotenvVars in data collector
  Add the missing translations for the Swedish ("sv") locale
  bumped Symfony version to 4.3.6
  updated VERSION for 4.3.5
  updated CHANGELOG for 4.3.5
  bumped Symfony version to 3.4.33
  updated VERSION for 3.4.32
  update CONTRIBUTORS for 3.4.32
  updated CHANGELOG for 3.4.32
  [Messenger] DoctrineTransport: ensure auto setup is only done once
  [Form][DateTimeImmutableToDateTimeTransformer] Preserve microseconds and use \DateTime::createFromImmutable() when available
  [Crawler] document $default as string|null

Author: nicolas-grekas

Caster/SymfonyCaster.php

@@ -33,7 +33,8 @@ public static function castRequest(Request $request, array $a, Stub $stub, $isNe
         $clone = null;
 
         foreach (self::$requestGetters as $prop => $getter) {
-            if (null === $a[Caster::PREFIX_PROTECTED.$prop]) {
+            $key = Caster::PREFIX_PROTECTED.$prop;
+            if (\array_key_exists($key, $a) && null === $a[$key]) {
                 if (null === $clone) {
                     $clone = clone $request;
                 }
@@ -47,7 +48,9 @@ public static function castRequest(Request $request, array $a, Stub $stub, $isNe
     public static function castHttpClient($client, array $a, Stub $stub, $isNested)
     {
         $multiKey = sprintf("\0%s\0multi", \get_class($client));
-        $a[$multiKey] = new CutStub($a[$multiKey]);
+        if (isset($a[$multiKey])) {
+            $a[$multiKey] = new CutStub($a[$multiKey]);
+        }
 
         return $a;
     }